Subject: [PATCH 2614/2944] x86/fsgsbase/64: Clean up various details

From: Ingo Molnar <[email-masked]>
Date: Fri, 19 Mar 2021 16:04:22 +0800

to #30648216

commit ec3a94188df7d28b374868d9a2a0face910e62ab upstream.

So:

 - use 'extern' consistently for APIs

 - fix weird header guard

 - clarify code comments

 - reorder APIs by type

Cc: Andy Lutomirski <[email-masked]>
Cc: Borislav Petkov <[email-masked]>
Cc: Brian Gerst <[email-masked]>
Cc: Chang S. Bae <[email-masked]>
Cc: Dave Hansen <[email-masked]>
Cc: Denys Vlasenko <[email-masked]>
Cc: H. Peter Anvin <[email-masked]>
Cc: Linus Torvalds <[email-masked]>
Cc: Markus T Metzger <[email-masked]>
Cc: Peter Zijlstra <[email-masked]>
Cc: Ravi Shankar <[email-masked]>
Cc: Rik van Riel <[email-masked]>
Cc: Thomas Gleixner <[email-masked]>
Cc: [email-masked]
Link: http://lkml.kernel.org/r/[email-masked]
Signed-off-by: Ingo Molnar <[email-masked]>
Signed-off-by: Ethan Zhao <[email-masked]>
Signed-off-by: Zelin Deng <[email-masked]>
Reviewed-by: Artie Ding <[email-masked]>
---
 arch/x86/entry/vdso/vgetcpu.c   |  1 +
 arch/x86/include/asm/fsgsbase.h | 22 ++++++++++++----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/arch/x86/entry/vdso/vgetcpu.c b/arch/x86/entry/vdso/vgetcpu.c
index edd214f..f86ab0a 100644
--- a/arch/x86/entry/vdso/vgetcpu.c
+++ b/arch/x86/entry/vdso/vgetcpu.c
@@ -14,6 +14,7 @@
 __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
 {
 	vdso_read_cpunode(cpu, node);
+
 	return 0;
 }
 
diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h
index 5e9cbcc..eb377b6 100644
--- a/arch/x86/include/asm/fsgsbase.h
+++ b/arch/x86/include/asm/fsgsbase.h
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _ASM_FSGSBASE_H
-#define _ASM_FSGSBASE_H 1
+#define _ASM_FSGSBASE_H
 
 #ifndef __ASSEMBLY__
 
@@ -9,14 +9,15 @@
 #include <asm/msr-index.h>
 
 /*
- * Read/write a task's fsbase or gsbase. This returns the value that
+ * Read/write a task's FSBASE or GSBASE. This returns the value that
  * the FS/GS base would have (if the task were to be resumed). These
- * work on current or on a different non-running task.
+ * work on the current task or on a non-running (typically stopped
+ * ptrace child) task.
  */
-unsigned long x86_fsbase_read_task(struct task_struct *task);
-unsigned long x86_gsbase_read_task(struct task_struct *task);
-int x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase);
-int x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase);
+extern unsigned long x86_fsbase_read_task(struct task_struct *task);
+extern unsigned long x86_gsbase_read_task(struct task_struct *task);
+extern int x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase);
+extern int x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase);
 
 /* Helper functions for reading/writing FS/GS base */
 
@@ -25,20 +26,21 @@ static inline unsigned long x86_fsbase_read_cpu(void)
 	unsigned long fsbase;
 
 	rdmsrl(MSR_FS_BASE, fsbase);
+
 	return fsbase;
 }
 
-void x86_fsbase_write_cpu(unsigned long fsbase);
-
 static inline unsigned long x86_gsbase_read_cpu_inactive(void)
 {
 	unsigned long gsbase;
 
 	rdmsrl(MSR_KERNEL_GS_BASE, gsbase);
+
 	return gsbase;
 }
 
-void x86_gsbase_write_cpu_inactive(unsigned long gsbase);
+extern void x86_fsbase_write_cpu(unsigned long fsbase);
+extern void x86_gsbase_write_cpu_inactive(unsigned long gsbase);
 
 #endif /* CONFIG_X86_64 */
 
-- 
1.8.3.1